Low-power miniature fluorescent and/or glow lamp



July 19, 1949.

C. MOREHEAD LOW POWER MINIATURE FLUORESCENT AND/OR GLOW LAMP Filed Nov. 8, 1945 Ara-ma V INVENTOR (Wit/46195 MUEE/fE/VD.

BY W

ATTORNEY Patented July 19, 1949 LOW-POWER MINIATURE FLUORESCENT AND/R GLOW LAMP Chalmers Morehead, East Orange, N. J assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 8, 1943, Serial No. 509,350

6 Claims. 1

This invention relates to negative glow lamps of small power which may also be used as fluorescent lamps.

The primary object of my invention, generally considered, is to produce a low wattage glow lamp operable on household alternating or direct current, and the envelope of which, if desired, may be coated with fluorescent material to in crease th visible light output.

Another object of my invention is to produce a lamp which contains electrodes, desirably forming extensions of the lead-in conductors, helically coiled and closely interspaced with respect to one another, said lamp having a gaseous filling, said electrodes being coated with electronemission material, and the lamp operable with a power consumption of the order of .1 Watt.

A further object of my invention is to provide negative glow lamps of the gaseous conduction type where the cathode and anode are closely spaced to provide very short are lengths, caesium being provided to reduce the ionization potential, and a large resistance being incorporated in the lamp base to cut down the current fiow to a very small amount.

A still further object of m invention is to provide a negative glow lamp in which the gaseous filling surrounding the electrodes comprises neon and krypton in such proportions that the generated radiation has an effect on fluorescent material similar to that of 2537 A. U. wave length.

An additional object of my invention is to provide a negative glow lamp of the gaseous conduction type containing electrodes to which is applied caesium for lowering the ionization potential.

Another object of my invention is th provision of a negative glow lamp of the gaseous conduction type containing small closely-spaced wire electrodes in a small envelope, the interior surface of which is coated with beryllium-free manganese-activated zinc silicate containing an excess of zinc.

Other objects and advantages of the invention, relating to the particular arrangement and construction of the various parts, will become apparent as the description proceeds.

Referring to the drawings:

Figure 1 is an elevational view of a lamp with a bayonet-type base, shown to scale and full size in the original drawing, and embodying my invention.

Figure 2 is an elevational view of a lamp with a miniature screw-threaded base, shown to scale and full size in the original drawing, and embodying my invention.

Figure 3 is an axial sectional view, of the lamp of Figure 2 showing the details, including the base-bulb connection by cement, to scale and enlarged.

Figure 4 is a transverse sectional view on the lines IV-IV of Figure 3, in the direction of the arrows.

Figure 5 is a transverse sectional View on the line VV of Figure 3, in the direction of the arrows.

Figure 6 is a use of my lamp.

Figure 7 is a circuit diagram illustrating another use of my lamp.

The present application relates to one of the new lamps which has been developed by reason of the war. It may have an envelope no larger than an ordinary marble and yet be of remarkable efficiency. If of the fluorescent type, it is adapted to give off more light than a watt neon glow lamp that consumes 2 /2 times as much power. It is believed to be the first instance of high efiiciency achievement with a modern fluorescent lamp in a miniature size. The energy economy is such that thirty of the lamps need no more than an ordinary electrical clock motor, thereby making such suitable for many military applications where a light indication is required and very little energy available. For example, one of these lamps might be used to mark a cache of supplies left unattended for months, using energy from dry cells. One could be used as a flashing lamp on life rafts. If made available after the war for household use, a lamp could be left burning constantly for six months to mark a stair step or key-hole, for an insignificant amount of electricity.

Referring now to the drawings in detail, like parts being designated by like reference characters, and first considering the Figures 1 to 5, inclusive, there is shown as one embodiment of my invention, a lamp H in Figure 1, and as another embodiment, a lamp H in Figures 2 to 5, inclusive, said lamps being adapted for operation on about volts A. C; or volts D. C. and identical except that the lamp of Figure 1 has a bayonet-type base 12 and desirably has no base-contained resistor, while that of said other figures has a screw-threaded miniature type base I2 desirably containing a resistor it in series with one of the leads M and prevented from electrically contacting the shell of said base by suitable insulation, such as a paper sleeve circuit diagram illustrating one 20. Said resistor may be a tiny ring of carbonimpregnated insulating material, so that its resistance, when used as illustrated, that is, where the circular arc portions are in parallel, is about 30,000 ohms or irom 25,000 to 35,000 ohms.

The envelope [5 is desirably of the miniature sphericartype; say about A in diameter, and contains a mount 16. The mount is very simply made, as by fastening the ordinary dumet leads to and i7 together with a bead IQ of glass, and coiling the end portions beyond said bead into interspaced helical form, as indicated at 19 and 2|, so that they lie within about 2 mm. from each other. These helical portions are to form the electrodes, and for that purpose, they are, at least one, but desirably both coated from the bead 8 to their ends with a mixture, indicated at 22 and 23, adapted to develop electron-emission material in the form of' free caesium on heating,

for the purpose of lowering the ionization potential. For that purpose, the mixture desirably consists of potassium dichromate KzCrzOr, and caesium dichromate CszCrzOr, with an admixture of metallic magnesium as a reducing agent. The

envelope I5 is desirably filled with a mixture of rare gases, such as 4 parts of neon and 1 part of krypton, by volume, with or without a trace of argon, say a small percentage of the order of /2%, and/or Xenon; 'at a pressure desirably between 12 and 30 mm, but even between and 40 mm. of mercury. In order to make it possible to use a liquid air trap'on the exhaust system, when the evacuated lamps are filled with the gas mixture, without loss of krypton through condensation, the partial pressure due thereto should not exceed '4 mm. Withthis consideration, the optimum gas mixture, consistsof 4 parts of neon to 1 partof krypton," by'voluinefiused at a pressure of about 20 mm.

Glow lamps with the above gas mixture, either with or without a fluorescent coating, will operate satisfactorily over a wide range of ambient temperatures and'at currents of the order of .001 ampere. The gas mixture results in a lower breakdown voltage than if'krypton alone were used. It is not objectionable if the krypton contains some xenon. "After "gas filling, sealing-in and seasoning'as by running at over-voltage, say 220 volts A. C. for aboutan hour, to develop the metallic caesium electron-emission material by chemical reaction, the lamp is assembled with a conventional base, with'or without a resistance element asillustrated in'Figure 3. Said resistance element l3, if used,"desirably fits over the exhaust tip 2 3, and the desired lead to which said resistance element 13 is connected being, therefore, that which'goes to the center contact 25, as distinguished from the shell 2-6.

If a fluorescent lamp is to be made of the device previouslydescribed, the interior surface of the bulb i5 is coatedwith a phosphor, which desirably consists of beryllium-free manganeseactivated zinc silicate with an excess of zinc. No other qualification other than that it passes through a IOU-mesh sieveis required. This particular phosphor is found to be more efficient for changing the ultra violet radiations, generated by the discharge between the electrodes, into visible radiationsof a' greenish hue. However, if desired, other phosphorsmay be employed, as to provide other color efiects.

If connected directly across a source of continuous power, a series resistance is necessary in order to control the current flow after the initial gas break-down. However, if flashes, rather than continuous light, are desired, a circuit such as shown in Figure 6 is desirably employed. In accordance with this circuit a lamp H is used across a source 21 of direct current, in series with a resistor 28 of desirably about i megohm capacity. Across the lamp leads, a condenser 39 is applied, desirably of a capacity of to 1 microfarad. If the flash is to be extended, a small resistance 3|, of say about 500 ohms, may also be used between the condenser and lamp, as in dicated, although this is not essential. In operation, the condenser 29 will slowly charge through the large resistor 23, until the break-down voltage of the lamp ii "is reached. When the condenser will discharge through said lamp, and the resistor 31 if employed, with the emission of a flash which will be repeated when the condenser 29 becomes sufficiently recharged. The spacing of the fiashings may therefore be controlled by controlling the value ofthe resistor 28, shown adjustable. A

Referring now to Figure '7, an arrangement is there shown where a series of lamps H maybe operated in parallel, as on an. Xmas tree, for example, from a low-power low-voltage source 32 which may be an ordinary automobile storage battery or a few dry cells. This particular source is connected through a vibrator '33, such as one of those used on automobiles for generating the B-power for the radio, and-from there to the primary winding 34 0f a step-up transformer 35, across the'secondary wind-iiig 38 of which are the lamps i l in parallel. The low voltage direct current is, by this arrangement, brokering) into intermittent current which isin'turn transformed to alternating current of'thedesired potential, ofsay about loilvolts. v

From. the foregoingv description it wiil be seen that I have developed an eiiicierit low power source oflight, which may take the form of a glow. lamp or a fluorescent lamp or small. size operable from a. convenientsource of: power.

Although preferred embodiments oh my in /en tion have been described, it will: be understood that modifications maybe made within the spirit and scope cfthe appended claims.

I claim:

1. A negative-glowlamp of-the gaseous-conduction type, comprising closely-spaced electrodes functioning as cathode and anode, arr enclosing envelope, electron-emission material disposed on at least one of saidelectrodes to lower the ionization potential, and a. gaseous filling in said envelope consisting oineon' and krypton, inthe proportion of about four parts of the former-to one of the latter, byvolume, whereby thegenerated radiations. have. an efiect on. fluorescent {material consisting of, beryllium-free, manganese-activatedzinc silioatewith. an. excess oi-zinc,

similar tothat of Iditlidti011 Of 253,7:A, U. Wayee.

l t t r o qf-sa d;enre qpebeins-ccated with the mentioned fluorescent materiahior, the;

development sib a ieht rom said a iaticn A ti -s ow ma Qt ea eous cos.-

duciien type, comprising eagerear dredress M 29. 9a

functioning as cathode, and anod envelope, electron-emisfiion rn at least one of, saideledtfodes tdlo B theiionization potential, and; a 'gas'eousi fin g, in Sign, envelope. comprisin ess ntially. a. preponderance. emm

of neon and a smaller proportion 'of' H whereby the generated radiations havean ei'fie ct on e e e tmater m t n o er llium.

free, manganese-activatedsine silicate with an excess of zinc, similar to that of radiations of 2537 A. U. wavelength, the interior of said envelope being coated with the mentioned fluorescent material for the development of visible light from said radiations.

3. A negative glow lamp of the gaseous conduction type comprising an enclosing envelope about three quarters of an inch in diameter, leads sealed through the outer wall thereof, internally held together and braced by a glass bead, and terminating in interior helical closely-spaced electrodes, a mixture on at least one of said electrodes for developing metallic caesium, a gaseous filling in said envelope consisting of about four parts neon and one part krypton, by volume, at a pressure of about twenty millimeters of mercury, the interior of said envelope being coated with phosphor consisting of beryllium-free, manganese-activated zinc silicate with an excess of zinc, for the purpose of changing the generated radiations impinging thereon to visible light, said envelope being tipped-off adjacent the points of entry of the leads, a ring-shaped resistor fitting over the tip so formed and with one terminal connected to one of said leads, a lamp base enclosing said tip and resistor, and a connection from the other terminal of said resistor to the center contact of said base.

4. A negative glow lamp of the gaseous conduction type comprising electrodes functioning as cathode and anode, an enclosing envelope the interior surface of which is coated with fluorescent material consisting of beryllium-free manmanganese-activated zinc silicate with an excess of zinc, electron-emission material disposed on at least one of said electrodes to lower the ionization potential, and a preponderance of neon and a smaller proportion of krypton in said envelope, whereby the generated radiations have an effect on said fluorescent material similar to that of radiations of 2537 A. U. wave length, to provide for the efiicient development of visible light.

5. A negative glow lamp of the gaseous conduction type comprising an enclosing envelope about three quarters of an inch in diameter, the interior of said envelope being coated with phosphor consisting of beryllium-free manganeseactivated zinc silicate with an excess of zinc, leads sealed through the envelope outer wall and terminating at closely spaced electrodes, a mixture on at least one of said electrodes for developing metallic caesium, a preponderance of neon and a smaller proportion of krypton at a pressure between 12 and 30 millimeters of mercury, in

said envelope, whereby the generated radiations have an effect on said phosphor similar to that of radiations of 2537 A. U. wave length, to efficiently generate visible light, said envelope being tipped off at a point adjacent said leads, a ring-shaped resistor fitting over the tip so formed and with one terminal connected to one of said leads, a lamp base with a center contact and enclosing said tip and resistor, and a connection from the other resistor terminal to the center contact of said base.

6. A negative-glow lamp of the gaseous conduction type comprising closely spaced electrodes functioning as cathode and anode, an enclosing envelope, electron-emission material disposed on at least one of said electrodes to lower the ionization potential, and a gaseous filling in said envelope comprising essentially a preponderance of neon and a smaller proportion of krypton, at a pressure between 12 and 30 mm. of mercury, whereby the generated radiations have an effect on fluorescent material consisting of berylliumfree, manganese-activated zinc silicate with an excess of zinc, similar to that of radiations of 2537 A. U. wavelength, the interior of said envelope being coated with the mentioned fluorescent material for the development of visible light from said radiations.

CHALMERS MORE-HEAD.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,316,967 Moore Sept. 23, 1919 1,858,698 Zons May 17, 1932 1,965,588 Foulke July 10, 1934 2,009,215 Abshagen July 23, 1935 2,020,723 Foulke Nov. 12, 1935 2,073,715 Stone Mar. 16, 1937 2,135,707 Gaidies Nov. 8, 1938 2,151,496 Beese Mar. 21, 1939 2,194,288 Aust Mar. 19, 1940 2,219,923 Henninger Oct. 29, 1940 2,297,940 Claude Oct. 6, 1942 2,298,581 Abadie Oct. 13, 1942 FOREIGN PATENTS Number Country Date 360,823 Great Britain Nov. 5, 1931 555,327 Great Britain Aug. 17, 1943 

